6urn:lsid:arphahub.com:pub:DE333E49-E4EE-5693-9BEF-D446E6301C98urn:lsid:zoobank.org:pub:55528528-5C97-4D79-A718-8B3D153B37CCJournal of Hymenoptera ResearchJHR1070-94281314-2607Pensoft Publishers10.3897/jhr.51.92199219Research ArticleTenthredinoideaBiodiversity & ConservationHabitats Ecosystems & Natural SpacesCenozoicEuropeAllochthonous blue spruce in Central Europe serves as a host for many native species of sawflies (Hymenoptera, Symphyta)KulaEmanuel1HolusaJaroslavholusaj@seznam.cz2RollerLadislav3ÚradníkMiroslav4Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech RepublicFaculty of Forestry and Wood Technology, Mendel University in BrnoBrnoCzech RepublicCzech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 1176, 165 21 Prague, Czech RepublicCzech University of Life Sciences, PraguePragueCzech RepublicInstitute of Zoology, Slovak Academy of Sciences in Bratislava, Dúbravská cesta 9, 845 06 Bratislava, SlovakiaInstitute of Zoology, Slovak Academy of Sciences in BratislavaBratislavaSlovakiaAndreja Hlinku 2586/20, 960 01 Zvolen, SlovakiaAndreja Hlinku 2586/20ZvolenSlovakia
Corresponding author: Jaroslav Holuša (holusaj@seznam.cz)
Academic editor: M. Prous
201629082016511591697519B007-FF9C-6912-FFE2-FF8B702CFFC59CCF2F81-753E-4A20-A79D-D698E85263561479321405201627062016Emanuel Kula, Jaroslav Holusa, Ladislav Roller, Miroslav ÚradníkThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.http://zoobank.org/9CCF2F81-753E-4A20-A79D-D698E8526356
In air-polluted mountain areas of the Czech Republic, including the Ore Mountains, pure forest stands of introduced blue spruce (Piceapungens) were established in the 1980’s. We studied the Symphyta (Hymenoptera) fauna in the canopies of these trees at four sites and in the canopies of adjacent Piceaabies trees at one of these sites by beating tree branches. For the first time, Nearctic blue spruce is reported as a host for 17 European species of Symphyta (sawflies). Diprionids in the genus Gilpinia were the most abundant sawflies on P.pungens and were more abundant on P.pungens than on the native Piceaabies. Spruce pamphiliids in the genus Cephalcia were also more abundant on P.pungens than on P.abies, while the abundances of representatives of the tenthredinid genera Pikonema, Pachynematus, and Pristiphora were similar on P.pungens and P.abies. Our results indicate that many species of European spruce Symphyta are able to use the allochthonous species P.pungens as a host.
Kula E, Holuša J, Roller L, Úradník M (2016) Allochthonous blue spruce in Central Europe serves as a host for many native species of sawflies (Hymenoptera, Symphyta). Journal of Hymenoptera Research 51: 159–169. doi: 10.3897/jhr.51.9219
Introduction
In Central Europe, P.abies (L.) Karst is the only native species of spruce (Schwenke 1978). Many introduced spruce species including of the blue spruce, Piceapungens Engelm, are occasionally cultivated in urban areas. Beginning in the 1980s, pure stands of P.pungens have been planted in an area of about 100 km2 in the air-polluted mountain regions of the Czech Republic. P.pungens was thought to require only modest soil resources, to have a high tolerance to sulfur oxide air pollution, and to have the ability to resist or avoid ungulate herbivores (Šika 1976, Tesař 1981, Balcar 1986, Jirgle et al. 1983, Kubelka et al. 1992). The assumption about high resistance to air pollution was found to be incorrect, however, because the needles of young P.pungens and P.abies exhibit the same degree of damage in response to air pollutants (Soukupová et al. 2001).
Many forest pests including many defoliators feed on spruce (Pschorn-Walcher 1982).
At least 34 species belonging to three families of Symphyta (32 species in Central Europe) feed on needles of native spruce in Europe. These feeders include Pamphiliidae with at least nine species of Cephalcia (Viitasaari 2002), Diprionidae with four Gilpinia species and Microdiprionfuscipennis (Forsius, 1911) (Kontuniemi 1960, Viitasaari and Varama 1987), and Tenthredinidae with 15 Pristiphora s.l. (Beneš and Křístek 1979, Kajmuk 1988), two Pikonema and three Pachynematus s.l. (Taeger et al. 1998). Pristiphoratenuiserra (Lindqvist, 1959), for which the host plant is unknown, may also be a spruce feeder (Holuša and Roller 2000). New generic nomenclature of Nematinae (Prous et al. 2014) has been omitted (Pikonema and Pachynematus are currently treated as members of a vast genus Euura) with respect to applied entomology.
Although the blue spruce P.pungens is planted in the extensive, air-polluted areas of the Czech Republic, the Symphyta fauna developing on this allochthonous plant have not been thoroughly studied. One reason is that serious outbreaks of pests have not occurred during the 25- to 30-year period following the establishment of pure stands of P.pungens in the Ore Mountains (Holuša and Holuša 2003).
The host status of P.pungens for European native Symphyta is unknown. The goals of this study were (i) to identify the sawflies that feed on P.pungens in the Czech Republic and (ii) to compare the abundances of these sawflies on the native P.abies and on the introduced P.pungens.
Methods
Sawflies were studied in three localities in the Ore Mountains (NW Czech Republic) (Table 1). Two localities (Jirkov, Dlouhá louka) had pure stands of P.pungens, and one locality (Sněžník) had a pure stand of P.pungens and a pure stand of P.abies that were 100 m apart.
Characteristics of studied stands.
Locality
Tree species
Geographic characteristics
Altitude (m asl)
Stand density
Age of stand [years]
Area/percentage of spruce forest in district
Native forest type
Annual mean temperature and total precipitation
[%]
Jirkov
P.pungens
50°33'11"N, 13°22'59"E
875
90
25–36
14.43 km2/
Fageto - Piceetumacidophilum
4–4.5 °C
15.4%
1050–1200 mm
Dlouhá louka
P.pungens
50°39'00"N, 13°38'04"E
865
70
34
29.37 km2/
Fageto - Piceetumacidophilum
4–4.5 °C
22%
1050–1200 mm
Sněžník
P.pungens
50°47'28"N, 14°04'33"E
576
70
27–31
4.87 km2/
Piceeto - Fagetumacidophilum
4.5–5.5 °C
4.5%
900–1050 mm
Sněžník
P.abies
50°47'30"N, 14°04'15"E
576
70
19
28.76 km2/ 26.6%
Piceeto - Fagetumacidophilum
4.5–5.5 °C
900–1050 mm
Sawfly larvae and adults were sampled by beating tree branches and collecting the falling insects on a sheet stretched on a 0.5 × 1 m metal frame. On each sampling date, 10 samples were collected at each of the four stands. For each sample, two branches were selected at random in the crowns of 10 trees, the branches were located from 0.7 to 2.5 m above the ground, and the sampled trees were in a line with 10 m between adjacent trees. Trees were sampled on 17 May, 15 June, 14 July, 15 August, 15 September, and 15 October 2007. Thus, one sample consisted of insects collected from one stand (a total of 20 branches on 10 trees) across all six sampling dates.
The collected insects were stored in 75% ethanol. Larvae were identified using the keys of Beneš and Křístek (1979), Battisti and Jiang-hua Sun (1996), Battisti and Zanocco (1994), Martinek (1988), and Zanocco and Battisti (1995). Very young larvae (first and second instars) were identified only to genus (Cephalcia, Gilpinia, and Pristiphora). The current knowledge of larvae allows the identification of some Pachynematus s.l. and Pristiphora s.l. only to the subgeneric level and are here referred to as the Epicenematus and Sharliphora species groups, respectively. Adult sawflies were identified using the keys of Beneš and Křístek (1979), Viitasaari (2002), and Zhelokhovtsev (1988). The nomenclature follows Taeger and Blank (2011), and host plants are given according to Taeger et al. (1998) unless stated otherwise.
The data of larvae per locality were not normally distributed. When the abundance of a sawfly species was > 10 on both P.abies and P.pungens at Sněžník, the values were compared with a Wilcoxon pair test in Statistica 12.0.
Results
In total, 748 larvae and 79 adults of 36 species of sawflies were collected (Table 2). Among the 36 species, 23 have been previously associated with spruce, and the 13 have been previously associated with other plant species (Table 2). Larvae obtained from the branches of P.abies (N=127) and P.pungens (N=621) belonged to 12 and 18 species of Symphyta, respectively.
Total numbers of sawflies (Hymenoptera: Symphyta) collected on P.abies and P.pungens in the Czech Republic (plus information on known host plants for each species of sawfly). The sawflies were collected from 20 branches per stand (two branches on each of 10 trees) in three P.pungens stands (at Jirkov, Dlouhá louka, and Sněžník) and in one P.abies stand (at Sněžník) on six sampling dates from spring to fall in of 2007. Sawfly species feeding on spruce are in bold. When the abundance of a sawfly species (larvae + adults) was > 10 on both P.abies and P.pungens at Sněžník, the values were compared with a Wilcoxon pair test (an asterisk indicates a significant difference, and n.s. indicates a non-significant difference). The information on known host plants is from Taeger et al. (1998) unless indicated otherwise.
Number of larvae
Number of adults
Known hosts
Sawfly species
On P.abies at Sněžník
On P.pungens at all three stands (and at Sněžník in brackets)
Wilcoxon pair test
On P.abies at Sněžník
On P.pungens at all three stands
Argefuscipes (Fallén, 1808)
1
1
Salix, Betula
Cephalcia sp.
5
17(4)
Cephalciaabietis (Linné, 1758)
11(1)
6
P.abies, P.obovata, P.koraiensis
Cephalciaalpina (Klug, 1808)
2
16(2)
P.abies, P.obovata, P.koraiensis, P.jezoensis
Cephalciaarvensis Panzer, 1805
16(7)
4
11
P.abies, P.obovata, P.koraiensis, P.jezoensis
Cephalciaerythrogaster (Hartig, 1837)
1(0)
1
P.abies, P.koraiensis
Cephalciafulva Battisti & Zanocco, 1994
1
6(2)
P.abies, P.koraiensis
Dineuravirididorsata (Retzius, 1783)
1
Betula
Dolerusgonager (Fabricius, 1781)
1
Poaceae
Dolerusnigratus (O.F.Müller, 1776)
2
Poaceae
Gilpinia sp.
17
84 (42)
2.36*
Gilpiniaabieticola (Dalla Torre, 1894)
19
98 (19)
0.00 n.s.
2
P.abies, P.obovata, Pinuspumila (probably missidentification, Karel Beneš pers. comm.)
Gilpiniahercyniae (Hartig, 1837)
2
134 (4)
0.80 n.s.
P.abies, P.obovata (In N. America P.glauca, P.sitchensis, P.pungens, P.mariana, P.rubens, P.pungens (Quarantine PEST data Sheet))
Gilpiniapolytoma (Hartig, 1834)
7
19 (19)
1.85 n.s.
P.abies, P.obovata, and P.smithiana (Viitasaari (1987))
Macrophyasanguinoleta (Gmelin, 1790)
1
Veronica, Galeopsis, Senecio
Pachynematuslichtwardti Konow, 1903
2
unknown
Pachynematus (Epicenematus)sp.
21
95(17)
0.65 n.s.
Pachynematusmontanus (Zaddach, 1883)
1
P.abies, and P.obovata (Popov and Kajmuk 2010)
Pachynematusstyx (Benson, 1958)
1
P.abies
Pachyprotasisrapae (Linné, 1767)
7
oligophagous
Pamphiliushortorum (Klug, 1808)
1
Rubus
Pikonemainsigne (Hartig, 1840)
1(1)
P.abies, and P.obovata (Popov and Kajmuk 2010)
Pikonemascutellatum (Hartig, 1840)
11
11(1)
1.94 n.s.
1
1
P.abies, P.obovata
Pristiphora sp.
17
39(12)
1.40 n.s.
Pristiphoraabietina (Christ, 1791)
2
6(4)
P.abies, P.obovata (Popov and Kajmuk 2010) , P.obovata and P.sitchensis (Kollar 2007, Austara et al 1984)
Pristiphoracompressa (Hartig, 1837)
8
41 (12)
0.92 n.s.
2
P.abies, and P.obovata (Popov and Kajmuk 2010)
Pristiphoradecipiens (Enslin, 1916)
4
15(6)
1
P.abies
Pristiphoragerula (Konow, 1904)
1
2(0)
P.abies
Pristiphoraleucopodia (Hartig, 1837)
2
2(0)
P.abies
Pristiphorapallida (Konow, 1904)
1
P.abies
Pristiphorapseudodecipiens Beneš & Křístek, 1976
6
6(0)
1
1
P.abies
Pristiphorarobusta (Konow, 1895)
1(0)
P.abies, and P.obovata (Popov and Kajmuk 2010)
Pristiphorasaxesenii (Hartig, 1837)
7(0)
P.abies
Pristiphora (Sharliphora)sp.
2
9(2)
Pristiphoranigella (Förster, 1854)
2
P.abies
Pristiphoraparva (Hartig, 1837)
1
P.abies
Tenthredoatra Linné, 1758
1
oligophagous
Tenthredomesomela Linné, 1758
3
oligophagous
Tenthredoolivacea Klug, 1817
2
oligophagous
Tenthredopsisornata (Serville, 1823)
3
Brachypodium
Tenthredopsisscutellaris (Fabricius, 1804)
1
15
Festuca, Poa, Dactylis, Elytrigia
Total
127
621
10
69
Five species in the genus Cephalcia were only found in small numbers and on several specimens of P.pungens, and two of these five species were found on P.abies (Table 2). The abundance of larvae belonging to Cephalcia species did not differ between samples from P.abies and P.pungens (Table 2).
Diprionids of the genus Gilpinia were the most abundant sawflies in the samples and represented 51.8% and 35.4% of the specimens collected from P.pungens and P.abies, respectively. Gilpiniaabieticola and G.hercyniae were the most numerous species, while G.polytoma was recorded exclusively in the P.abies and P.pungens stands at Sněžník. Although the Gilpinia abundancy did not differ between P.abies and P.pungens stands, more first and second instar larvae of Gilpinia were found on P.pungens than on P.abies at Sněžník (Table 2).
Almost identical species (both larvae and adults) of spruce tenthredinids (Pristiphora, Pachynematus, and Pikonema) were found in the P.abies and the P.pungens samples, and the abundance of larvae of each species did not differ on P.abies vs. P.pungens. Based on larvae, Pachynematus (Epicenematus) sp. followed by Pristiphoracompressa were the most abundant species in P.pungens samples (Table 2).
Across all species, sawfly abundance did not statistically differ on P.abies vs. P.pungens at Sněžník (z=0.59, p>0.05).
Discussion
In the current study, a total of 18 sawfly species were collected from P.pungens in the Ore Mountains of the Czech Republic. This represents 56% of the species of needle-feeding spruce sawflies in Central Europe (N=32) (Beneš and Křístek 1979, Holuša 2005, Jachym et al. 2005). P.pungens was recorded as a new host for 17 of these Palaearctic species. The 13 additional species have not been associated with spruce as a host, and their occurrence in the samples was accidental (Table 2).
In Central Europe, eight species of Pamphiliidae are associated with P.abies (Holuša et al. 2007). We confirmed that P.pungens is a host for C.abietis, C.arvensis, C.alpina, C.fulva, and C.erythrogaster. In Europe, the most abundant sawfly has been C.abietis followed by C.arvensis, and mass outbreaks of C.abietis (Escherich 1942, Pschorn-Walcher 1982, Kula 1987, Liška et al. 1991) and local outbreaks of C.arvensis and C.alpina have been repeatedly reported (Křístek and Švestka 1986, Martinek 1991, 1992, Liška 1999, Zanocco and Battisti 1995).
The most abundant larvae collected from P.pungens were species of Gilpinia. All three spruce diprionids (G.abieticola, G.hercyniae, and G.polytoma) are common in spruce stands in Central Europe (Úradník and Kulfan 2002, Holuša and Roller 2004), but the three species can differ in abundance, dominance, and frequency (Martinek 1960, Úradník and Kulfan 2002, Holuša and Roller 2004). Untill this study, G.hercyniae has been the only European diprionid known to feed on P.pungens (Balch 1939).
The numbers of spruce tenthredinids in the genera Pikonema, Pristiphora, and Pachynematus were similar on P.pungens vs. P.abies. We suspect that the L1 and L2 larvae identified as Pachynematus (Epicenematus) sp. are P.montanus, although Pachynematus (Epicenematus) pallescens (Hartig, 1837) and the extremely rare P.styx may also be present in the studied stands. The former species has the ability to rapidly increase (Kolubajiv 1939, Martinek 1994, Reisenberger and Krehan 1993) and is widespread not only in P.abies stands (Holuša 2002) but also in P.pungens stands (this study). Another species that can rapidly increase, Pikonemascutellatum, was rarely collected in the study area, although it is common in Central Europe (summarised by Holuša and Lubojacký 2008). Because one adult of the very rare species Pikonemainsigne was found in the P.pungens stand at Sněžník, we suspect that P.pungens is a host for this species.
The larvae of eight Pristiphora species plus adults of P. (Sharliphora) pallida and P. (Sharliphora) parva were collected on P.pungens, but it is very probable that larvae of Pristiphora (Sharliphora) sp. were represented mainly by the larvae of Pristiphoranigella. P.abietina is a pest of Norway spruce in Central Europe (Pschorn-Walcher 1982) and often occurs in high numbers with Pikonemascutellatum and Pachynematusmontanus (Kolubajiv 1939, 1958). However, P.abietina prefers lower altitudes where it can rapidly increases (Martinek 1960, Holuša 2002). Thus, the low abundance of this species in the studied stands is in accordance with the aforementioned studies. P.compressa, the most common Pristiphora in P.pungens stands, could be even more abundant than P.abietina in mountain stands of P.abies (Úradník and Kulfan 2002). We also found P.pallida and P.robusta, that have been very seldom recorded in spruce stands (Forsius 1911, Křístek 1973).
In the investigated air-polluted areas the native P.abies stands are almost completely absent because this tree was not used for forest regeneration in the 1980’s (Kubelka et al. 1992). Our study indicates that a range of P.abies defoliators use P.pungens as a substitute host plant. This phenomenon has also been documented for herbivorous moths. Of the 50 moth species that feed on P.abies in Europe, 31 have been found to develop on the needles and buds of P.pungens (Kulfan et al. 2010).
The spruce-feeding sawflies in Central Europe are not strictly monophagous on P.abies. Most of these species have been observed to feed on other Palaearctic spruces like Piceaobovata (Ledeb.), Piceakoraiensis Nakai, and Piceajezoensis (Sieb. & Zucc.) (Taeger et al. 1998). Before the current study, however, Nearctic spruces had not been reported as hosts for European Symphyta other than for G.hercyniae (Balch 1939).
Because the abundance of sawfly larvae and adults was low in the current study (compare with Holuša 1999, Holuša and Lubojacký 2008), we did not observe substantial defoliation of trees in the P.pungens stands in 2007. Severe defoliation of P.pungens was reported in the 1970s and early 1980s even at altitudes of 900 m (Holuša and Holuša 2003). Many sawfly outbreaks occurred throughout the Czech Republic in the early 1980s. The most recent instance of severe defoliation and subsequent chemical treatment was in 1982 (Holuša and Holuša 2003). The regeneration of P.abies stands has recently increased in the Ore Mountains (Šrámek et al. 2008), and thus populations of sawflies living on P.pungens may recolonize the P.abies stands in the future. Although sawflies have not recently caused extensive damage to spruce in Central Europe, the spruce sawflies are in a latency period in this region (Holuša et al. in prep.), and local outbreaks have occasionally occurred (Egginger et al. 2014).
Conclusions
Our results demonstrate that European spruce sawflies are able to use the diverse allochtonous spruce species as hosts and may show stronger preferences for the new host, here especially P.pungens, than for the native host, P.abies.
Acknowledgements
This study was supported by grants VZ MSM 6215648902 “Forest and Wood: the support of functionally integrated forest management and use of wood as a renewable raw material“, and EHP-CZ02-OV-1-044-01-2014 “Frameworks and possibilities of forest adaptation measures and strategies connected with climate change“. The study was also sponsored by the following companies and organizations: Netex Co. (Děčín), Nadace ČEZ Co. (Prague), Lafarge cement (Čížkovice). The authors thank Dr. Bruce Jaffee (USA) for critically reading the manuscript.
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